1) Field of the Invention
The latching hydroseal valve is a normally closed two-position, three-way valve. The latching hydroseal valve can be installed on or in a control pod that operates a Christmas tree, which is installed on a subsea wellhead for production of oil and/or gas. The control pod will typically include more than a dozen latching hydroseal valves used for various control functions. The latching hydroseal valve is connected to a source of pressurized pilot fluid and a downstream apparatus. The latching hydroseal valve is also connected to a source of pressurized supply fluid to selectively direct such supply fluid to a downstream apparatus in response to fluid signals from the pilot fluid. A typical downstream apparatus is a valve actuator. The actuator typically controls a gate valve, which regulates well flow through the tree.
2) Description of Related Art
The latching hydroseal valves of the present invention are rated for operational pressure up to 20,000 psi and are designed to operate in sea water that is up to 10,000 feet deep. Competitive products sometimes referred to as directional control valves are currently manufactured by Mandeville Engineering Limited of Maidenhead, Berkshire, U.K.; Scana Rotator as, of Nodeland, Norway (the U.S. subsidiary is Scana Industries, Inc. of Houston, Tex.); Tactair Fluid Controls, Inc. of Liverpool, N.Y.; Cameron Controls and ABB Seatech Controls.
An advertising brochure for hydraulic directional control valves from Scana Rotator is included in the Information Disclosure Statement filed concurrently herewith Scana produces a number of different hydraulic directional control valves at least one of which is similar to the present invention, model number 91.11.11.13-3.2. A section drawing from Scana of this directional control valve is likewise included in the Information Disclosure Statement. The Scana directional control valve model number 91.11.11.13-3.2 is used in similar situations to the present invention. However, this particular Scana valve uses a large number of seals and the design is complicated and expensive to manufacture. The present invention uses a bi-directional seal which results in fewer total seals and ultimately reduces the chance of leakage. In addition, the design of the present invention is less complicated and more economical to manufacture.
U.S. Pat. No. 6,116,276 issued to Grill, discloses a dynamically balanced, latching fluid valve. This valve includes a solenoid and spring assembly sealed by a pair of seals that each have an effective area approximately equal to the effective area of the valves. Activation of the solenoid moves a tube and valve from a first position allowing fluid communication between a cylinder port and a supply port and then to a second position, allowing fluid communication between a cylinder port and a return port. The spring latches the valve to the first position. The solenoid is actuated by short digital pulses that latch the transfer tube and valve into position. The Grill valve is apparently formed of plastic and is used for purposes such as in applications of insecticides. It is unlikely to be suitable for subsea applications.
U.S. Pat. Nos. 4,258,749 and 4,355,661 to Mayer disclose pneumatic pressure control valves having two oppositely acting solenoids. The structures disclosed in the Mayer patents include a central valve body which interposes two housing sections, each having a central member functioning as a valve guide and each housing also being adapted to mate with one of two ends of the central valve body. Thus, sandwiching one of two independently actuatable solenoids therebetween. The solenoids cooperate with a central valve body and housing section to form an actuation chamber. Each solenoid contains a movable element of the house slidably disposed with each actuation chamber and each valve guide. This device is intended to solve problems related to control valves, especially pneumatic control valves to modulate the fluid pressure applied to vacuum actuators. It can also be modified for use as an on-off control valve using only a single solenoid.
The latching hydroseal valve of the present invention has a latching function that is achieved through differential diameters in the seal carrier. In addition, the present invention has a bi-directional seal. Fewer seals in the present invention reduces the chance of leakage when compared to prior art designs. The present invention is also less complex and more economical to produce than prior designs.
The latching hydroseal valve is a normally closed, two-position, three way valve. The latching hydroseal valve is connected to at least one source of pressurized pilot fluid and a downstream apparatus. The latching hydroseal valve is also connected to a source of pressurized supply fluid to selectively direct such supply fluid to a downstream apparatus in response to fluid signals from one or more pilot valves.
Typically the latching hydroseal valve is connected to two upstream pilot valves. Actuation of one pilot valve opens the latching hydroseal valve and actuation of the other pilot valve closes the latching hydroseal valve. Typically the upstream pilot valves are normally closed, two-position, three way valves. In modem systems, these two position, three way pilot valves are typically pulsed or actuated for approximately 2-3 seconds and then they are turned off. When they are turned off, they vent the pilot fluid. The pilot fluid between the pilot valve and the latching hydroseal valve is vented to atmosphere as well as the pilot fluid in the latching hydroseal valve itself. The present invention has a latching feature that will allow the latching hydroseal valve to stay in the open position when the pilot vents to atmosphere. The latching hydroseal valve will not close until the other pilot valve is actuated; unless there is a failure of supply pressure.
In more modern designs, a single pilot dual pulse spool valve may also be suitable for controlling the latching hydroseal valve in lieu of two upstream pilot valves. The single pilot dual pulse spool valve is disclosed in U.S. patent application Ser. No. 09/948,846, Filed on Sep. 7, 2001, and is incorporated herein by reference. The single pilot dual pulse spool valve patent application is owned by Gilmore Valve Co., the assignee of the present application.
In an alternative embodiment, two solenoid pilot valves are connected to the latching hydroseal valve and a source of pressurized pilot fluid. The latching hydroseal valve is also connected to a source of pressurized supply fluid to selectively direct such supply fluid to a downstream apparatus in response to fluid signals from the solenoid pilot valves.
The latching hydroseal valve has a main seal assembly with a bi-directional seal. This bi-directional seal reduces the total number of total seals required in the valve and allows for a more simple design than the prior art. The chance of leakage and malfunction has been reduced in the present invention because the total number of seals has been reduced. In addition, the present invention is a more simple design that is easier and more economical to produce than the prior art.
The latching hydroseal valve can be produced with or without a close assembly. In the preferred embodiment, the latching hydroseal valve is produced with a close assembly to guard against unexpected drops in supply pressure. The purpose of the close assembly is to close the latching hydroseal valve if supply pressure unexpectedly falls below a minimum set pressure. The close assembly can be manually adjusted in the field by rotation of an elongate adjusting bolt to raise or lower the set pressure. In an alternate embodiment, the close assembly is not manually adjustable in the field. In this alternative embodiment, the spring itself determines the set pressure. The set pressure is predetermined during manufacture of the valve by selection of an appropriate spring.